Protective arrangement



W. DIESENDORF PROTECTIVE ARRANGEMENT Original Filed Nov. 2'7, 1935 Fig.2.

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PROTECT IVE ARRANGEMENT July 16, 1935.

Original Filed NOV. 27, 1953 2 Sheets-Sheet 2 Fig.5.

Inventor": Walter Diesirjfij,

His Att,

OFT? e3 Patented July 16,1935 2,008,544

UNITED STATES PATENT OFFICE 2,008,544 PROTECTIVE ARRANGEMENT Walter Diesendorf, Vienna, Austria, assignor to General Electric Company, a corporation of New York Application November 27, 1933, Serial No. 699,956. Renewed May 31, 1935. In Germany December 15, 1932 8 Claims. (Cl. 175-294) My invention relates to improvements in prodistance relay windings I I and I2 are further tective arrangements for electric systems and connected at their end points through contacts more particularly to improvements in protective l8 of ground relay I and bridging member I9 to arrangements wherein selectivity is obtained on two cross-connected current transformers 20 and 5 the basis of the distance of a fault from the st-a- 2| in the phase conductors 5 and 1 respectively. 5

tions of the system. An object of my invention The bridging member I9 is operated by the is to provide for polyphase alternating current ground relay I5 in such a manner that when electric systems a distance type of protective arit bridges the contacts 22, the current transrangement wherein only a single distance type formers 29 and 2I are short-circuited. An imrelay is necessary for protection against faults pedance 23 arranged in parallel with the cur- 10 regardless of the number of phase conductors rent windings of the distance relay I3 is coninvolved in a fault. nected in circuit on the simultaneous operation My invention will be better iuiderstood from of the relays I6 and I! through their series rethe following description when considered in lated contacts 24 and 25, respectively. The

connection with the accompanying drawings and voltage winding 26 of the distance relay I3 is ar- 15 its scope will be pointed out in the appended ranged to be connected by the bridging members claims. or contacts 21, 28, 29 and 30 associated with the In the accompanying drawings, Fig. l illusrelays I5, I6 and I I to a polyphase potential trates diagrammatically a distance type of protransformer 3| in a manner which will appear tective arrangement embodying my invention; in connection with the explanation of the op 20 Figs. 2, 3 and 4 illustrate diagrammatically proeration of the protective arrangement. The tective arrangements embodying modifications contacts for the voltage circuit are so arranged of my invention. that the voltage coil, in case of a fault between In accordance with my invention, in order to two phase conductors, is energized by the voltobtain correct distance response with only one age between the affected conductors and, in case 25 distance relay regardless of the number of phase of a fault between one phase conductor and conductors involved in the fault, I provide means ground, by the voltage to ground of the affected for insuring a substantially constant distance phase conductor. factor measurement or time of operation for all In case of a short circuit between phase confaults at a given location on the basis that each ductors 5 and 6, a current dependent on the fault 30 different kind of fault has of itself the same imcurrent in the phase conductor 5 will appear in pedance characteristic, for example the same the current windings II and I2 of the distance ohmic impedance, resistance or reactance derelay I3 from the current transformer 20. The pending on which one of these the relay is deovercurrent relay I6 will respond and through its 5 signed for operation. In this connection I probridging member 2'! close its contacts 32. The vide means which, on the occurrence of a ground ground relay I5 will not operate and its contacts fault, change the current excitation of the relay I8, 33 and 34 will remain closed, as shown. Confrom phase conductor current to asymmetrical or sequently, the voltage coil 26 of the distance relay zero phase current and the potential excitation I3 is connected to be energized from the potential from voltage between phase conductors to volttransformer 3| in accordance with the voltage 40 age from a phase conductor to ground. between the phase conductors 5 and 6 in an ener- Referring now to Fig. 1, there are installed in gizing circuit including the contacts 32 of the a three-phase circuit 5, 6, I three current transrelay IS, the contacts 33 of the relay I5 and the formers 8, 9 and I0 asymmetrically connected contacts 38 of the relay II. In case of a fault 4.3 through the current windings II, I2 of the startbetween the phase conductors 6 and I, the curlog and timing elements respectively of a dis rent windings II and I2 of the distance relay I3 tance type relay I3 and the winding I4 of a will be energized in accordance with the current ground or zero phase sequence current relay I5. of the phase conductor I through the current The circuit 5, 5, I is shown as arranged to be transformer 2|. The voltage winding 26 of the controlled by a latched closed type of circuit distance relay I3 will be connected to be ener- 50 breaker 40 having a trip coil 4I. Auxiliary regized from the potential transformer 3| in aclays I6 and II have their energizing windings dicordance with the voltage between the phase conrectly connected in series with the current ductors 6 and I in a circuit including the contacts transformers 8 and II! so as to be energized in 35 of the overcurrent relay II, the contacts 33 of accordance with the currents in the phases. The the relay I5, the contacts 39 of the relay I6 and 5 the o ontacts 35' of the relayll'.

circuit in parallel to the current windings i l and I2 of the distance relay so as to reduce the amount of current supplied to thesewindings to one half of the fault current as reflected in the two current transformers 28' and 2!. Obviously, the operation of the contacts 23 and 25 may be effected either through electrical ormechanical dependence of the over-current relays it and ii.

The voltage coil 25 will be connected to be energized'from the potential transformer ti in'ac cordance with the voltage between the phase conductors Eandl in a circuit through the contacts 32'of-the overcurrent' relay it the contacts 33 of th'ejrelay l5 and thecontacts 35 of the overcurrentrelay ll. In case of a fault involving all .of the phase conductors and'l, the ove'rcurrent relays l6 and El will close their contacts 25,

-32 and-'25, 35, respectively. 7 The current windings of the distance relay will accordingly receive one half of the current reflected in the current tr a-nsformers2dfl' and the voltage winding will be energized from the potential transformer Si in accordance with the voltage between the phase'conductors 5 and 5; Thus, in all faults involving: at least two' phase conductors, the relay I3 is controlled in accordance with twice the phase impedancebetweenth point at which the relay'is' located and the point of fault.

'In case 'ofafault to groundfon any phase con ductor, the relay 5 responds to close its contacts 22'; stands-1. 'The currentwindings H and EZ-of the distance relay are thus disconnected from the current transformers 263 and 25 and are con- 'nected to'be energized by the asymmetrical or zero phase sequence'current reflected in the current transformers 8, S and it. At the same time the voltage windingv 253 is connected through the contacts=3l of the relay if to the neutral of the secondary windings of the potentialtransforn'ier 3| andthrough the contacts of the'relays i5, i6; 1

and li-l toa voltage corresponding to the voltage toground'cf theiphase conductor affected by the fault. Thus, for aground faulton phase conductor 5 the relays l 5 and I5 operate and'the circuit of the voltage'winding 261s energized by the .voltage' to' ground of the phase conductor 5 fault on the phase conductor 7, the relays l5 and, I!operate. In this case the voltage winding 26 iS' ene'rgiZedin accordance with the voltage to ground of'the phase conductor 'l' through a circuit whichincludesthe' contacts and 3? of the relay lithe contacts 39 of the relay l6 and It hasbeen assumed that on the occurrence of sho'rt circuits the current in the path'from thelocation'of" the selective relay to the short circuit or fault point 'willmeet the same imcontacts, however, remains the'same.

peda'nce in the phase conductor as on the return path through ground or through a neutral conductor. This is generally the-case but when short circuit reaotances are installed in the network, then with a fault between two phase conductors, the current will on its outgoing and return path in the phase conductors flow twice through the conductor impedance and twice through the reactances while in case of a line to groundfault it will pass only once through the cond ctorimpedance on its outgoing path and the reactance and on its return path through theground conductor which may be'assumed to be equal to'the phase'conductor impedance. In this case the impedance of the reactance coil is effective but once. Consequently, the selective relay will measure a distance from the fault which is too small. In order to avoid this in case of a ground fault the current which is active in the current windings of the distance relay should be reduced as compared with the actual value of the asymmetrical current in the same ratio as that of the impedance of the current loop, (Z+ZE) with a ground fault to rent transformers having the sarnetransforma tion ratio are used, the same result can be obtained by connecting in the asymmetrical circuit an intermediate current transformer having the corresponding transformation "ratio. The difference between the impedances 22. and

Z+ZE' in case of a fault between phase conductors and a fault between a phase conductor and ground, respectively, may, however, be compensated by'increasing the voltages to ground supplied. An intermediate potential transformer should have a'ratio of with two current windings, one of which is connected in the asymmetrical circuit and the other to'the current transformers 2 and 28 in the arrangement shown. The arrangement of the Moreover, it is further possible in designing the windings to allow for the different impedances in case of a fault between phase conductors and a fault between a phase conductor and ground.

In order to reduce the cost of the equipment, it is possible to use but three high voltage current transformers, as shown in Fig. 2. In this case the: current transformers 28 and 2! are connected in the secondary circuits of the transformers 8 and It, considerable allowance being made for the transformation ratio. The connections are otherwise the same. In the embodiinent of my invention shown in Fig. 2, however, instead of using the overcurrent starting relays l5 and'il, I have shown undervoltage starting relays l'til'and HE which are connected to be energized from those secondary windings of the potential transformer 31 which'are associated with 'the'phase conductors 5 and 7; Also the startingelement of the distance relay l3, in addi Obviously the distance relay may be furnished 2,008,544 tion to the current winding II, is provided with an opposing voltage winding 42 by means of which overcurrent starting dependent upon the voltage is obtained as is desirable in networks having different possible short circuit currents in accordance with the connected generating capacity. When the starting relay responds, the contacts 43 will be closed and the voltage winding 26 of the distance relay I3 energized.

In the embodiment of my invention shown in Fig. 3, only three current transformers 8, 9 and III are necessary. These are connected in star and are combined to form another star point through the windings of the overcurrent transfer relays 44 and I6, the star point being connected through the current windings II and I2 of the distance relay and through the current winding I4 of the ground relay I5 to the first star point of the current transformers. The ground relay I5 includes contacts 45 and 46 for controlling the circuits of the current windings of the distance relay. In circuit with the winding of the overcurrent relay I! are included contacts 41 and 48 of an auxiliary relay 49, the contacts 48 being connected between the overcurrent relays I1 and 44 and the contacts 4'! being connected between the overcurrent relay I1 and the current windings of the distance relay I3. The auxiliary relay 49 is operated when a fault occurs between the phase conductors 6 and I because under these conditions the overcurrent relay I6 would be in the position shown with its contacts 59 closed and the overcurrent relay I'I will be energized to close its contacts 5| thereby completing the circuit of the relay 49 from a suitable source 52. Thus the auxiliary relay 49 is energized when overcurrent occurs in the phase conductor 1 if there is not at the same time an overcurrent condition in the phase conductor 5. Obviously a mechanical interlock in place of the electrical interlock shown can be used.

The voltage winding 26 of the distance relay I3 has its energizing circuit controlled with reference to the potential transformer 3| through the contacts 33, 31 of the ground current relay I5, the contacts 32, 39, 52 and 53 of the overcurrent relay I6, the contacts 54 and 55 of the overcurrent relay 44 and the contacts 35, 38, 56 and 51 of the overcurrent relay IT. The contact arrangement in the voltage circuit differs from that in Fig. 1 essentially in the fact that the normally open contacts 52 and 56 of the relays I6 and II, respectively, are in circuit with one terminal 56 of an auxiliary transformer 59. This transformer is so constructed and arranged as to supply a voltage to the winding 26 of the same phase as the voltage to ground of the phase conductor 5 but double the magnitude thereof as reflected in the potential transformer secondary 3|. In this way it is possible for the selective relay to measure twice the phase impedance in case of a fault involving all of the phase conductors 5, 6 and I as well as in the case of a fault involving only two of these phase conductors.

The operation of the embodiment of my invention shown in 3 is as follows: In case of a fault involving the phase conductors 5 and 6 or the phase conductors 5 and I or all of the phase conductors, neither the ground current relay I5 nor the auxiliary relay 49 is operated. The distance relay, therefore, receives current proportional to the current in the phase conductor 5 in each of these three cases of faults and the voltage coil 26 will be momentarily connected to be energized in accordance with the voltages between the phase conductors affected by the fault. Thus, with a fault involving the phase conductors 5 and 6 the circuit of the voltage coil 26 includes the contacts 32 of the overcurrent relay I6, the contacts 33 of the ground current relay I 5, the contacts 54 of the overcurrent relay 44 and the contacts 51 of the overcurrent relay I'I. With a fault involving the phase conductors 5 and 'I, the energizing circuit of the voltage coil 26 includes the contacts 32 of the relay IS, the contacts 33 of the relay I5 and the contacts 55 of the relay 44. In case of a fault involving all of the phase conductors 5, 6 and I, all of the overcurrent relays I6, 44 and I! operate. In this case the voltage winding 26 of the distance relay is connected across the transformer winding 59 in a circuit which includes the contacts 32 of the overcurrent relay I6, the contacts 33 of the relay I5, the contacts 54 of the relay 44, the contacts 52 of the relay I6 and the contacts 56 of the relay I1. Consequently, the voltage coil 26 is energized in accordance with twice the line to line voltage, as previously explained. In case of a fault between the phase conductors 6 and I the auxiliary relay 49 will be energized because the contacts 56 of the relay I6 remain closed and the contacts 5| of the relay I! are closed in response to the operation of this relay. As the result of the operation of the relay 49 both of the current transformers 8 and III will be connected to the current windings of the distance relay. Inasmuch as the phase conductor 5, however, is not carrying fault current, only the current of phase conductor I will be affected by the distance relay. In this case the voltage winding 26 of the distance relay will be connected to be energized in accordance with the voltage between the phase conductors 6 and "I in a circuit which includes the contacts 35 of the relay II, the contacts 32 of the relay I6, the contacts 33 of the relay IS, the contacts 54 of the relay 44 and the contacts 53 of the relay I5.

In every case of a fault to ground, the relay I5 will operate. Thus, in each case of a fault to ground, regardless of whether or not the auxiliary relay 49 is operated, the current windings I I and I2 of the distance relay will be connected between the two points common to the current transformers 8, 9 and I D and will, therefore, be energized in accordance with the asymmetrical current. In consequence of the operation of the ground fault relay I5 and some one of the relays I6, 44, I1 depending upon the phase conductor affected by the ground fault, the voltage winding 26 of the distance relay will be connected to be energized in accordance with the phase voltage which is affected by the ground fault. This also applies to the voltage winding 42 of the starting element which is connected in parallel with the voltage winding 26. Thus, for a ground fault on the phase conductor 5 the energizing circuit of the voltage winding 26 includes the contacts 32 of the relay I6 and the contacts 31 of the relay I 5. In case of a fault to ground on the phase conductor 6, the circuit of the voltage winding 26 includes the contacts 51 and 38 of the relay I1, the contacts 39 of the relay I6 and the contacts 3'! of the relay I5. For a ground fault on the phase conductor I the energizing circuit of the voltage winding 26 includes the contacts 35 of the relay II, the contacts 39 of the relay I6 and the contacts 31 of the relay I5. In every case, therefore, the relay will measure twice the .in the winding 62.

phase impedance in caseof a; ground fault as-in the case of afaultbetweenphase conductors.

in order to obtain fault currents, three windings,

BI, 52, 63; are arranged on a common iron core 64. The winding 6i isconnected between the current transformers 8 and 9- and the winding 62 is connected between the current transformers 9 and iii. The common point. between the wind-' ings 6! and 52 which is connected to the current transformer 9 is normally connected to the neutral point of the current transformers 8. and H3 through the contacts 65 of the relay M. The shunt impedance 5% is connected between theend of the winding iii through the contacts 26 of the relay l6 andthercontacts 25 of the relay H. The contacts are closed on the simultaneous response of the relays i6 and ii. The voltage winding 26 of the distance relay is connected,

through contacts associated with the relays l5, l6, Mend ii to the potential transformer 3! in such a way that the voltage affected bythe fault,

whether it be between thephase conductors or from a phase conductor to ground, is momentarily effective in the distance relay. 7

In case of a fault between the phase conductors 5 and 6, fault current will appear only in the winding tl'and the overcurrent relay M will operate. However, as there is no asymmetrical current, the operation of this relay will have no effect The voltage winding-26 will be connected to be energized in accordance with the voltage between phase conductors 5 and 6 in a circuit including thecontacts 32 of the relay it, the contacts 38 of the relay-l1 and the contacts 33 of the'relay 15. The operationof the relay 44 will have no effect so far as this is concerned. In case of a fault between the phase conductors 6 and l, fault current will appear in the winding 62. The voltage winding 26 will be connected to be energized in accordance with the voltage between the phase conductors E5 and l in a circuit including the contacts 55 of the relay Mi, the contacts 39 of the relay i 6 and the contacts 35 of the relay ii. In case of a fault between the phase conductors 5 and l, fault current will appear in the windings 6i and 62. Due, however to the operationof the relays l6 and H, the shunt impedance 66' will be connected in circuit through the contacts 24 of the relay i8 and the contacts 25 of the relay ii. The current, therefore, will be reduced to the same value as in the case of a fault between the phase conductors- 5 and 6 or 6 and I. The voltage winding 26 will be connected to be energized in accordance with the voltage between the phase conductors' and I in a circuit including the contacts 32 of the relay l5 and the contacts 35 of the relay H. In case of a fault involving all of the phase conductors 5, 6 and l, the conditions are thesame as for a fault between the phase conductors 5 and 1.

In case of a fault to ground on the phase conductor 5, ground fault current will appear in the winding 6|. In case of a ground fault on the phase conductor 1, ground fault current appears In case of a fault to ground on the phase conductor 6, the relay 34 will operate and through its contacts 6'! connect the winding 63 in circuit to be energized inaccordance with the fault current in the phase conductor 6.

to set 7 For the purpose or adding the proper amount. of

zero sequence current to the actual phase current excitation of the windings 68 or 62 or 63 there may be included a Winding 68' so as to insure that the indicated distance of the relay incase of line to ground faults is correct where line to ground potential excitation is used for the voltage coils of the distance relay. In case of a ground fault on the. phase conductor 5, the relays l6 and i5 will operate. and the voltage winding 26 will be energized in accordance with the voltage to: ground of the phase conductcor 5 in a circuit including "the. contacts 32 of the relay l5, contacts 38 of,

the relay l'l'and the contacts ST-o-f the relay iii.

In case of a line to ground fault on thephase conductor 6 the relays M and I5 will operate and the voltage coil 26 of the distance relay will-be connected to be energized inaccordance with the voltage to ground ofthe phase conductor 6 in a circuit including the contacts 55 of the relay 44,

the contacts 38 of the relay Hi, the contacts 38 of the relay I! and the contacts 3"! of the relay contacts 65, 6? come into operation only in a single short circuit case. Obviously, the windings 6|, 62 and 63 may be directly associated with the distance relay or with an intermediate transformer through the secondary winding of which the distance relay is connected. 7

While I have shown and described my invention in considerable detail, I do not desire to be limited to the exact arrangements shown but seek to cover in the appended claims all those modifications that fall within the true spirit and scope of my. invention. 7

' What I claim as newand desire to secure by Letters Patent of the United States is:--'

1. In a protective arrangement for a polyphase alternating current circuit wherein selectivity is obtained on the basis of the location of a fault,

a single phase distance relayhaving current and ofsaid current and voltage windings to maintain the distance response characteristic of said relay substantially constant for faults at a given location independently of the number of phase conductors involved in said faults.

2. In a protective arrangement fora threephase alternating current circuit wherein selectivity is obtained on the basis of the location of afault, a single-phase distance relay having current and voltage windings connected tobe energized from the circuit and fault responsive means connected to be energized from said circuit for controlling the connections of said current and voltage windings to'maintain the distance response characteristic of said relay substantially constant for single-phase faults," three-phase faults and ground faults at a given location.

3. In a protective arrangement for a polyphase alternating current circuit wherein selectivity is obtained on the basis of the location of a fault, a single-phase distance relay having current and voltage windings connected to be energized from F said circuit and means for controlling the connections of said current and voltage windings to maintain the distance response characteristic of said relay substantially constant for faults at a given location independently of the number of phase conductors involved in said faults including a relay connected to be energized in accordance with the zero phase sequence component of the circuit current and at least two relays respectively connected to be energized in accordance with the currents of two phase conductors of the circuit.

4, In a protective arrangement for a polyphase alternating current circuit having a grounded neutral wherein selectivity is obtained on the basis of the location of a fault, a single-phase distance relay having current and voltage windings and means responsive to abnormal circuit conditions for connecting the current winding of the distance relay for with the current in a faulted phase conductor of the circuit for faults between phase conductors and in accordance with the asymmetrical current of the circuit for ground faults and for connecting the voltage winding for energization in accordance with the voltage most affected by the fault to maintain the distance response characteristic of the relay substantially constant for faults at a given location independently of the number of phase conductors involved in said faults.

5. In a protective arrangement for a polyphase alternating current circuit wherein selectivity is obtained on the basis of the location of a fault, a single-phase distance relay having current and voltage windings connected to be energized from said circuit and means for controlling the connections of said current and voltage windings to maintain the distance response characteristic of said relay substantially constant for faults at a given location independently of the number of phase conductors involved in said faults including a relay connected to be energized in accordance with the zero phase sequence component of the circuit current.

energization in accordance 6. In a protective arrangement for a polyphase alternating current circuit wherein selectivity is obtained on the basis of the location of a fault, a single distance relay comprising a distance element having current and voltage windings and a starting element having a current winding, the windings of said elements being connected to be energized from said circuit and means responsive to abnormal circuit conditions for connecting the current windings of said elements for energization in accordance with the current in a faulted phase conductor of the circuit for faults between phase conductors and in accordance with the asynnnetrical current of the circuit for ground faults, said responsive means including means for connecting the voltage winding of the distance element for energization in accordance with the voltage most affected by the fault.

'7. In a protective arrangement for a polyphase alternating current circuit wherein selectivity is obtained on the basis of the location of a fault, a single-phase distance relay having current and voltage windin s connected to be energized from the circuit and means responsive to ground faults on the circuit for selectively efiecting the energization of said current winding in accordance with the current of the grounded phase conductor and for selectively effecting the energization of the voltage winding in accordance with the voltage most affected by the fault.

8. In a protective arrangement for a polyphase alternating current circuit wherein selectivity is obtained on the basis of the location of a fault, a single phase distance relay having current and voltage windings connected to be energized from the circuit and means responsive to interphase and ground faults for selectively effecting the energization of said current winding in accordance with the fault current and for selectively effecting the cnergization of the voltage Winding in accordance with the voltage affected by the fault.

WALTER DIESENDORF. 

